455 Swap

[88hurstolds]

To give others an idea of what it takes to install a 455 in a G-body I am posting the progress of the swap. It's easier than you think stuffing one of these under the hood.

I started with a cleaned out engine bay and a 7a headed '72 Olds 350 that was built in Q1 of '73 (notice the rare factory bronze 'Oldsmobile' valve covers, these only came blue in '73).
I didn't bother to detail the engine bay since it was a daily driver and the mosquito fogging 307 needed to be quickly swapped so I could get to work.



The A/C, cruise control emissions and ECM were ditched and a heater box was installed. Notice the red wires wrapped up on the right side, they are both power wires, one is for the ECM and the other is for the A/C. These can be saved to run anything requiring 12v.

Don't be deterred if you want to save your A/C system, a heater box is not required and there is plenty of space under the hood still for the 455.
Here is a link on how to save your A/C system:

http://www.78-88olds.com/forum/showthread.php?t=12

(yes I know the PCV valve is disconnected...)
I completely removed all necessary wiring by following wiring leading from the ECM up to the steering column, cruise control, fuse box and gauge pack. Instead of having to fabricate a plate for the ECM harness hole I just sawed the harness flush with the rubber grommet on both sides.

I also found a non-ECM kick panel from an 84 Diesel Cutlass Calais with the same Sand Gray color interior to clean things up further in the interior. Will post some pictures later.

[quick86silver]

any update?

[88hurstolds]

Engine and trans are pulled, motor is being painted and the engine bay is being degreased. Been torn between painting it 68-69 Red or VHT Ceramic Black. I might make a sleeper out of it and paint it black, probably look cleaner since it is a daily driver. I also want to return the aircleaner to stock black as well.

[HurstOlds]

What car are you dropping this into? What kind of MPG's do you expect to get? Are you running a 3 speed or 4 speed? And what rear gear are you running, thx

[88hurstolds]

It's an 84 Cutlass Calais / 83 H/O clone. I don't care about MPG's... lol I only commute 20 miles a day and I am running a 7 5/8" 3.73 Posi with a TH-2004R. Previously I was running a 350/TH350 with the 3.73 Posi and wasn't doing to well on the MPG's, I think I was getting between 10 and 12 MPG's which isn't that bad. The car is very light so I think that helped.

[Pontiacman469]

This may sound numb:But is Mpg an issue when you have a 455?Do you power or Mpg,Mine was around 7 last time i checked w/ 4:10s but if i wanted to save at the pump i'd go with a mild 350.12-15 would be nice tho...:icon14:

[88hurstolds]

Well I have the engine in and almost ready to fire, the site is having a few problems with the attachment uploader since I updated the site. Should have that fixed tonight and get some pictures up.

[88hurstolds]

Here are a few pictures of the progress after detailing, painting and installation, I decided to go with the black look to keep it looking stock.

The motor dropped right in with no changes to the motor mounts making this a very easy swap. I have a heater box but if you have an A/C box you will not run into any problems.
The stock 307 alternator, starter and PS pump will all bolt right up as they did in my 88 Cutlass with a 455 which still has the factory A/C (I will post some pictures of how to mount the A/C pump in another thread). I had to use about a 1.2" spacer (bunch of washers) for the lower alternator bracket where it bolts up to the power steering pump to compensate for the added 1.2" deck height of a 455.
However I may go with a passengers side alternator to help balance the weight distribution and to avoid premature WP bearing failure due to uneven belt force distribution.

The stock manifolds were kept to clear the steering shaft. I also swapped the RH manifold from the 350 to keep the correct exhaust connection since SB and BB manifolds will interchange.
Olds had two different styles of RH manifolds where they bolted up to the exhaust pipe. One had an exit that was slightly angled and could cause an issue with the fire wall while the other one's exit stayed parallel with the ground, this manifold is the harder of the two to find as I have been told but I believe most 307 G-body's came with this style and will bolt up to the 455 just so long as you keep the 455 crossover pipe which fits in with no clearance issues. The 86-88 stock exhaust manifolds will not bolt up due to the port sizing of the roller 307 motors.
There are a few options out there for 455 G-body headers such as Hooker Super Comp and Kooks, which is now owned by Dick Miller Racing, but are rather expensive and I am trying to use as many stock components as possible to make this a cheep upgrade.


The 455 is stock with J heads and has been rebuilt; it will be upgraded to C heads, Ebrock intake and a few other extras in the next few weeks along with dual exhaust. Water pump, brackets, distributor and wiring are going on this week to give it a test run before I pull the manifold and heads...

[smokelessfire]

Looks pretty clean, does the air cleaner fit under there?

[88hurstolds]

I though it wouldn't but the dual snorkel barely fits under the hood with no issues. The body mounts must still be really good

[88hurstolds]

Well it's finally done, after a few vacations, concerts and other things taking up my time I finally got it out on the road today and all I can say is, it's fast and the video doesn't do it justice... :icon14:
I spun the tires and hit 2nd at 30 but I had it shift into 2nd at 60mph before... I'll fix that by adjusting the TV cable and installing the Lighting Rods tomorrow.
It finally shifted into 3rd at 60mph and 4th gear at 80mph...

http://www.youtube.com/watch?v=WRHIVhBilUY

I used the pulley's from the 455 and the brackets from the 307, I could have just used the pulley's from the 307 but they have the AIR and A/C provisions and I didn't want the extra rotational weight. I had to use a spacer (bunch of washers) for the lower alternator bracket where it bolts up to the power steering pump.
That was about the only modification needed for this swap otherwise everything bolted right up. The dual snorkel air cleaner even clears the hood, I have heard that this is an issue but that was not the case. However it is an issue with Ebrok intakes and you have to run a 2" drop unit or a super skinny eBrock one like this pictured on my 84 Calais when I first bought it:

[ralph442]

sweet. puttin my 86 back on the road tommorrow. 71 455, built 200-4r, 3.42 peg leg. can't wait.

[Pontiacman469]

My 2cents:Paint the Valve covers,Intake...Dont know bout the loud fan shoud.But Looks Awesome!:icon14:

[88hurstolds]

Intake was swapped out for a performer, valve covers are going to be chromed eventually...

[gator2206]

Hey man looks really good. Looks like the Olds factory did it.I like the black valve covers only thing I'm not real keen on is the red fan shroud but individuality is what makes our hobby great